CLINICOPATHOLOGICAL ANALYSIS OF FOLLICULAR LYMPHOMA WITH A POLYPLOID KARYOTYPE

The prognostic significance of specific cytogenetic abnormalities in f ollicular lymphoma (FL) is an area of ongoing research. A small percen tage of FL are characterized by a polyploid karyotype. Several studies have analyzed ploidy level to determine its role as an independent pr ognostic factor in non-Hodgkins lymphoma, with equivocal results, most ly using DNA flow cytometry to ascertain ploidy status. We have perfor med cytogenetic analyses on 180 cases of FL with a t(14;18) diagnosed between 1980 and 1995. Cases were divided into a polyploid group (20 c ases) and a non-polyploid group (160 cases), polyploidy defined as a m odal chromosome number of 58 or greater. Each group included examples of the 3 subtypes of FL, [Working Formulation]: 1) follicular small cl eaved cell (FSC), 2) follicular mixed, small and large cell (FM), and 3) follicular large cell (FLC). The median follow-up time was 38.5 mon ths. The histological subclassification of the polyploid group reveale d much less FSC (30% vs 66%, p < 0.004) and much more FLC (25% vs 4%, p < 0.003) than the non-polyploid group, implying histological progres sion may occur in parallel with the development of polyploidy. Recogni zed clinical prognostic factors were evenly distributed between the tw o groups and no survival difference was detected. We show that polyplo idy as determined by classical cytogenetics is present in different fr equencies across the subtypes of FL with a t(14;18), but is not an ind ependent prognostic factor for survival in FL.